I Have Recently Began Itching And Occasionally Breaking Out In

I have recently began itching and occasionally breaking out in hives. It seems that it occurs after I take a shower or when I'm really cold I start itching all over. It feels like my "blood is crawling" through my veins and that makes me itch. I don't drink a lot of water and was wondering if that has anything to do with it.
Thank you!
Carlene Wesley